## What changed
- Upgrade `rmcp` from 3.0.0 to 3.1.2.
- Use `rmcp`'s native JSON-RPC decoding and remove the local compatibility layer for multi-round-trip tool results.
- Preserve response metadata on `input_required` SSE results.
- Support OAuth protected-resource metadata discovery and include the discovered resource audience when refreshing tokens.
## Testing
- Add coverage for metadata preservation on modern SSE `input_required` responses.
- Add an OAuth startup scenario that discovers protected-resource metadata and verifies the refresh-token resource audience.
GitOrigin-RevId: 689f009b4a33552b640304111b74585b4009eeb8
## Why
MCP requests can contain sensitive headers and tool-call bodies. Following a
cross-origin redirect could disclose them to another server.
## What changed
- Follow redirects only when every hop remains on the configured server's
origin, and require HTTPS for redirects on non-loopback hostnames.
- Preserve standard redirect method and body handling while sharing the
original timeout and enforcing a 10-hop limit.
- Avoid replaying plaintext proxy credentials across redirects, while leaving
OAuth requests that stop at redirects unchanged.
## Testing
Add coverage for same-origin and cross-origin redirects, redirect methods,
headers and bodies, proxy credentials, timeouts, hop limits, and legacy MCP
tool calls.
GitOrigin-RevId: 3e267911a1665ad8c2fc63825099a758770f4d68
## Why
Headers configured for an MCP resource can contain credentials and must not be
forwarded to a different origin during OAuth discovery, registration, or token
exchange.
## What changed
- Apply configured resource headers only to OAuth requests on the MCP resource
origin, while allowing OAuth-generated headers to take precedence.
- Follow credentialed OAuth redirects only when each destination remains on the
resource origin. Preserve redirect method semantics, the overall timeout, the
response size limit, and a maximum of 10 redirects.
- Use the Codex MCP user agent for requests to authorization-server origins.
## Testing
Add coverage for cross-origin header isolation, same-origin dynamic client
registration redirects, OAuth header precedence, token refresh, timeout
accounting, and response size limits.
GitOrigin-RevId: 609d06e2b065e4aa9ca5382b4ae60455f9e26db9
## What changed
- Add `http_headers_helper` configuration for local streamable HTTP MCP servers. The configured shell command runs once per connection and returns a JSON object of headers that is cached across requests.
- Apply helper headers to MCP startup and OAuth flows while restricting them to the server origin, stopping redirects, rejecting reserved or duplicate headers, and enforcing output and execution limits.
- Reject helpers for remote or managed-disabled servers, use the local environment working directory, and redact helper commands from `codex mcp list` and `codex mcp get` output.
## Testing
- Cover configuration validation, helper lifecycle and output parsing, origin isolation, OAuth discovery and token refresh, managed requirements, environment selection, and CLI redaction.
GitOrigin-RevId: 84e0e26ce75520b0869d37c72b1678e033bd6818
## Why
Local stdio MCP servers may start in a different working directory from Codex,
so inherited relative CA bundle paths can otherwise resolve to the wrong file.
## What changed
- Forward the supported custom CA environment variables to local stdio MCP
servers, convert inherited non-empty paths to absolute paths, and let explicit
MCP environment overrides take precedence.
- Match CA variable names and `PATH` case-insensitively where required, avoiding
duplicate environment entries and preserving executable discovery on Windows.
## Testing
- Add an end-to-end stdio MCP test covering relative inherited CA paths, empty
values, explicit overrides, alternate key casing, and a different server
working directory.
- Exercise executable resolution with Windows-style `Path` casing.
GitOrigin-RevId: ea1bc0ae63bc0dc780acb8363b2ed102120f282e
## What changed
- Expose hosted Plugin Runtime event definitions through `McpResourceClient::list_events`.
- Add cancellable `events/stream` subscriptions that route lifecycle notifications to the matching request and cancel when the stream is dropped.
- Bound event notification and queue sizes, time out stalled response headers, and close streamable HTTP responses locally on cancellation.
## Testing
- Add streamable HTTP integration coverage for isolated concurrent subscriptions, local cancellation, and stalled response-header timeouts.
GitOrigin-RevId: 98c6fffa8f004eb2638c1b0705f659222cbbdfdb
## Why
A local stdio MCP server can exit while its descendants remain alive. Cleaning up
only the server process can therefore leak processes after client shutdown.
## What changed
- Contain locally launched MCP servers in non-breakaway Windows job objects and
terminate the job during shutdown so descendants exit with the server.
- Preserve compatibility when job creation or assignment is unavailable by
retrying without containment and terminating an owned process handle instead.
- Use the process-group member fallback when terminating piped processes on
macOS.
## Testing
- Cover descendant cleanup and breakaway prevention for both local MCP protocol
modes on Windows.
- Cover the Windows nested-job assignment fallback and verify the suspended
process resumes before handle-based termination.
GitOrigin-RevId: 33d3cc122de8f7ce0ae69a649b12ea0ff64b7c6f
## Why
An OAuth-backed Streamable HTTP MCP server can fail startup when its stored credentials are rejected. If a client then completes OAuth sign-in and replaces those credentials, the failed server needs to become available without restarting the Codex session.
## What changed
- Track the credential store and OAuth tokens used for each MCP connection, and detect replacements after authentication failures.
- Refresh affected MCP servers before the next turn and include their recovered tools in the model request.
- Classify HTTP authentication challenges and rejected refresh tokens as requiring reauthentication, with sign-in guidance appropriate to local and client-managed environments.
## Testing
- Cover recovery from expired credentials through an externally written replacement token.
- Cover authentication-error classification, startup messaging, and `Auto` store migration from file credentials to the keyring.
GitOrigin-RevId: 9b090089d4e7a44ffc182f4e25da20a18e97b70f
## What changed
Extend the executor-backed Streamable HTTP timeout test to cover both legacy
`initialize` and MCP 2026 `server/discover` requests. Verify that each stalled
handshake times out and releases the serial executor for subsequent requests.
GitOrigin-RevId: 3493904433c95265b9f645813723e890b7610abb
## Why
A streamable HTTP MCP handshake could time out while its executor-backed HTTP
request continued running, leaving the serial executor blocked for later
requests.
## What changed
- Track the remaining initialization deadline for streamable HTTP transports.
- Apply it to `initialize`, `notifications/initialized`, and discovery HTTP
requests, then clear it when the handshake finishes.
## Testing
- Added a regression test that stalls the remote MCP endpoint, waits for the
handshake timeout, and verifies that a subsequent executor request completes.
GitOrigin-RevId: d4980a332e898309c885cbaa4fdd598924b440e1
## What changed
- Track Agent Plugin manifests through plugin, skill, and MCP loading so their capabilities use format-specific behavior without changing legacy plugins.
- Discover only direct-child skills, exclude app and hook capabilities, isolate MCP data, and reject MCP configuration files that are non-regular or resolve outside the plugin root.
- Bound model-visible skill instructions, plugin instructions, MCP descriptions, schemas, individual tools, and the aggregate Agent Plugin MCP tool set.
- Stop MCP and OAuth redirects when Agent Plugins send configured or authorization headers, while retaining existing redirect behavior for legacy MCP servers.
## Testing
- Add coverage for capability filtering, skill discovery, isolated MCP data and reserved-path expansion, unsafe MCP configuration files, context limits, and redirect handling.
GitOrigin-RevId: c9af66b051269f3226628ca280a58d32c808c38f
## What changed
- Update the Rust MCP SDK from `3.0.0-beta.3` to `3.0.0` and adapt to its renamed metadata and server discovery types.
- Accept discovery responses without server identity metadata, using the configured server name as a fallback, and rely on the SDK's native support for namespaced server identity metadata.
- Preserve typed OAuth HTTP errors so transport failures, cross-origin redirects, and transient HTTP responses are reported instead of being treated as anonymous access.
## Testing
- Cover modern discovery with namespaced or missing server identity over HTTP, SSE, and stdio.
- Cover OAuth discovery error propagation for transport failures, redirects, and transient status codes.
GitOrigin-RevId: 12c1e45136cca89ce4fb15986c2b5df14608682a
## Why
Some legacy MCP servers reject `server/discover` before creating a session and
return a null-ID JSON-RPC error with a non-JSON content type or without echoing
the rejected protocol version. These responses prevented the client from
falling back to legacy initialization.
## What changed
- Parse HTTP 400 discovery errors without a session ID regardless of their
declared content type.
- Fall back to `initialize` when error code `-32000` reports a missing session
or advertises only known legacy protocol versions, including supported
versions other than `2025-06-18`.
- Continue rejecting unrelated error codes, correlated responses, non-400
statuses, malformed version lists, and lists containing modern or unknown
versions.
## Testing
Added MCP discovery coverage for legacy error variants, server-selected legacy
protocol versions, non-JSON content types, and non-legacy rejection cases.
GitOrigin-RevId: 4d3ee2d7d852ce0d0ab3f486da23cb653a7ff5ca
## What changed
- Require callers to provide an HTTP client for MCP OAuth discovery and login, removing the separate direct `reqwest` path.
- Use the shared `http` and `url` types throughout the MCP client and drop its direct `reqwest` dependency.
- Preserve configured MCP headers when routing OAuth discovery through the provided client.
## Testing
- Add coverage that routed OAuth discovery forwards configured headers.
GitOrigin-RevId: 1345f56bd794626533133447597a5908e57b9b48
## What changed
- Drive multi-round `tools/call` and `resources/read` requests through
`input_required` responses, preserving opaque request state and elicitation
metadata across JSON, SSE, and stdio transports.
- Decode modern discovery and elicitation result shapes while retaining legacy
initialization, elicitation defaults, and discovery fallback behavior.
- Apply the 8 MiB modern-protocol response limit to JSON, SSE events, and stdio
messages, and reject executor stream recovery when output sequence gaps would
corrupt the protocol stream.
## Testing
Added integration coverage for discovery, multi-round requests, legacy
fallbacks, message limits, stdio launchers, SSE responses, session recovery,
and executor output recovery.
GitOrigin-RevId: d26a08883a2825e8ce2408ac498114b33859225e
## What changed
- Add an opt-in `mcp_2026_07_28` protocol mode while preserving the legacy
lifecycle by default.
- Negotiate the new protocol over streamable HTTP with `server/discover`,
including bounded responses, redirect protection, and fallback only when a
response establishes that the endpoint is legacy-only.
- Require stdio servers to opt in with
`CODEX_MCP_PROTOCOL_VERSION=2026-07-28`, and add a bounded local stdio
transport for the modern lifecycle.
- Consume paginated tool, resource, and resource-template catalogs in modern
mode, reject repeated cursors, and retain discovered server identity.
- Reconnect reusable MCP clients when their selected protocol mode changes.
## Testing
- Cover HTTP JSON and SSE discovery, legacy fallback and rejection cases,
redirects, retries, response limits, and pagination.
- Cover local and executor stdio discovery, protocol markers, message limits,
and legacy compatibility.
GitOrigin-RevId: f6a78816e127d2a482292d63b91c8384f1595903
## What changed
- Update the `rmcp` model and transport integrations for `3.0.0-beta.3`.
- Preserve legacy `elicitation/create` form requests, schema defaults, metadata, and wire-format compatibility while adopting the new elicitation types.
- Harden OAuth discovery by using GET-first discovery without starting an MCP session, preventing cross-origin header redirects, validating authorization-server and callback issuers, and retaining compatibility with metadata that omits an issuer.
- Keep stored OAuth credentials readable and avoid requiring reauthorization after transient refresh failures.
## Testing
- Add coverage for legacy elicitation round trips, OAuth discovery variants, callback issuer validation, credential migration, and refresh failures.
GitOrigin-RevId: 756197d26f3fd347c28c400228f6b3d06ed493b7
## Why
Remote environment connections need to honor Codex's effective outbound proxy policy, including when a rendezvous connection reconnects.
## What changed
- Pass the configured `HttpClientFactory` into remote environment transports and use `WebSocketConnector` for exec-server and rendezvous WebSockets.
- Resolve proxy routes asynchronously so these connections can use the configured system proxy.
- Add connector options that preserve Tungstenite's default TLS behavior and enable `TCP_NODELAY` for latency-sensitive rendezvous traffic.
## Testing
- Verify prepared remote environments connect through a configured system proxy.
- Verify initial and reconnected encrypted relay peers use the system proxy.
- Cover default TLS selection and opt-in `TCP_NODELAY` behavior in the WebSocket client.
GitOrigin-RevId: 8a8da2116e37cb3a891269d0c0b037986fecdd3c
## What changed
- Send `codex-mcp-client/<version>` as the default user agent for streamable HTTP and OAuth requests.
- Preserve user agents supplied through configured HTTP headers.
## Testing
- Verify the default user agent on OAuth discovery, token refresh, and MCP initialization requests.
- Verify that a configured user agent overrides the default.
GitOrigin-RevId: 659ef8f126df97b3c1b4d01e9e542a673b5ef42b
[Codex Thread
019edd6d-6f14-74e2-853c-345d1803d4a6](https://codex-thread-link.openai.chatgpt-team.site/thread/019edd6d-6f14-74e2-853c-345d1803d4a6)
## Stack
Review and merge in order. Every layer is independently correct and
documents its safe stopping point.
1. [openai/codex#30292](https://github.com/openai/codex/pull/30292) —
aggregate File/Secrets store locking
2. [openai/codex#30293](https://github.com/openai/codex/pull/30293) —
resolve and lifecycle-pin the exact OAuth store
3. [openai/codex#30416](https://github.com/openai/codex/pull/30416) —
serialized authoritative refresh transaction
4. [openai/codex#30294](https://github.com/openai/codex/pull/30294) —
Codex-owned transport refresh and one-shot 401 recovery
5. [openai/codex#30295](https://github.com/openai/codex/pull/30295) —
login/logout transaction serialization
6. [openai/codex#30296](https://github.com/openai/codex/pull/30296) —
diagnostic-only Auto store drift reporting
**This PR is layer 2.**
## Why
`Auto` is keyring-first with a File fallback, but re-evaluating that
policy during transport reconstruction or persistence can make one MCP
client read from one store and later write to another. With rotating
refresh tokens, the second store may contain an older token. This layer
makes the source selected at client startup explicit and keeps that
authority stable for the client lifecycle.
## What this PR does
- Keeps `resolve_oauth_tokens_from_store_policy` as the single
configured-policy entry point and returns both credentials and the
concrete File or Keyring source that supplied them.
- Puts exact `load`, `save`, and `delete` operations on
`ResolvedOAuthCredentialStore`, making “resolve configured policy” and
“use the selected authority” distinct at call sites.
- Pins the first concrete source in `pinned_credential_store` in the
transport recipe, so initialization retries and session reconstruction
cannot re-evaluate `Auto` and adopt another store.
- Gives `OAuthPersistor` the resolved store and keeps subsequent
persistence and removal on that authority.
- Uses a typed keyring-load error to distinguish aggregate-store
coordination failures from ordinary backend failures; a coordination
failure is surfaced instead of triggering File fallback.
- Keeps login-time `Auto` behavior unchanged: prefer Keyring, fall back
to File when unavailable, and clean up legacy File state after a
successful keyring save.
- Adds structured server/backend context when fallback cleanup fails.
## Explicit decisions and non-goals
- The selection is lifecycle-local and in memory. This PR does not add a
durable backend selector, migration, reconciliation registry, or global
source of truth outside `CODEX_HOME`.
- `Auto` may choose File at the start of a later process if keyring
availability changes. Once this client resolves, a selected-store
failure is returned instead of hot-switching.
- Different `CODEX_HOME` instances remain independent even when they can
access the same Direct keyring credential.
- Cross-process refresh serialization is intentionally not part of this
layer.
## Safe stopping point
This PR can merge alone. A single MCP client no longer hot-switches
credential stores across transport rebuilds or persistence. Two
processes can still refresh the same selected credential concurrently
until layer 3.
## Review size
The net layer is 9 files, +668/−144. The production change remains
focused on store resolution and lifecycle pinning; the largest follow-up
is integration coverage that drives real session recovery.
## Validation
- `just test -p codex-rmcp-client` (99 passed; 5 expected skips)
- Real-client 404 recovery coverage with different Keyring and File
tokens; captured bearer headers prove the stale File token is never sent
- Mutation check: removing the lifecycle pin makes that integration
regression fail by observing the stale File token
## Summary
- classify authentication-required RMCP startup failures, including
errors nested inside `ClientInitializeError::TransportError`
- let `codex-mcp` consume that classification so the existing
`reauthenticationRequired` startup failure reason is emitted
- add a regression test that performs real startup with an expired
persisted OAuth token and no refresh token
## Why
Follow-up to #29877.
RMCP stores streamable HTTP initialization failures inside a dynamic
transport error whose payload is not exposed through the standard Rust
error source chain. The original `anyhow::Error::chain()` check
therefore missed the nested `AuthError::AuthorizationRequired` seen
during real MCP startup and emitted `failureReason: null`.
The transport-specific inspection now lives in `codex-rmcp-client`,
while `codex-mcp` consumes only the domain-level authentication-required
result. This classifier does not distinguish first-time login from
reauthentication; the existing auth-state logic remains responsible for
that distinction.
## User impact
When stored MCP OAuth credentials are expired and cannot be refreshed,
app clients now receive `failureReason: "reauthenticationRequired"` on
the failed startup update and can show the reconnect action. First-time
login and unrelated startup failures remain unchanged.
## Validation
- `just test -p codex-rmcp-client --test streamable_http_oauth_startup
identifies_expired_unrefreshable_token_startup_error`
- `just test -p codex-mcp
startup_outcome_error_identifies_authentication_required`
- `just test -p codex-mcp
mcp_startup_failure_reason_requires_existing_oauth_and_auth_failure`
- `cargo build -p codex-cli --bin codex`
- local app-server probe emitted `failureReason:
"reauthenticationRequired"`
- manual end-to-end reconnect flow confirmed
- `just fmt`
## Summary
- distinguish expired, non-refreshable stored MCP OAuth credentials from
first-time missing credentials
- carry a typed `failureReason: "reauthenticationRequired"` on the
existing `mcpServer/startupStatus/updated` notification only when user
action is required
- keep the public MCP auth-status API unchanged and regenerate the
app-server protocol schemas and documentation
## Why
An MCP server with an expired access token and no usable refresh token
currently fails startup without giving clients a reliable, typed
recovery signal.
The existing startup-status notification is the natural place to carry
this state. Its nullable `failureReason` keeps the recovery reason
attached to the failed startup transition without adding a one-off
notification. Internally, Codex distinguishes first-time login from
reauthentication and emits the reason only when the startup error itself
requires authentication.
## User impact
App clients can prompt an existing user to reconnect an MCP server when
automatic recovery is impossible by handling a failed
`mcpServer/startupStatus/updated` notification whose `failureReason` is
`reauthenticationRequired`. Starting, ready, cancelled, unrelated
failures, and first-time setup carry no reauthentication reason.
## Companion app PR
- openai/openai#1069582
## Validation
- `just test -p codex-app-server-protocol` — 248 passed; schema fixture
tests passed
- `cargo check -p codex-app-server -p codex-tui`
- `just test -p codex-rmcp-client -p codex-mcp` — 184 passed, 2 skipped
- `just test -p codex-protocol -p codex-app-server-protocol -p
codex-mcp` — 579 passed
- `just write-app-server-schema`
- `just fmt`
## Why
Remote stdio MCP servers can run in an environment whose path convention
differs from the Codex host. A Windows cwd such as
`C:\Users\openai\share` is absolute for the executor but was rejected by
a POSIX orchestrator.
Built on #29501, now merged, which only clarifies the host-native
`PathUri` constructor name.
## What changed
- Deserialize MCP cwd values as `LegacyAppPathString` so config does not
apply host path rules.
- Interpret that spelling as host-native for local launches and convert
it to `PathUri` at executor launch.
- Skip host filesystem and command resolution checks for remote stdio in
`codex doctor`.
- Add host-independent config and executor-boundary coverage using the
foreign path convention for each test platform.
## Validation
- `just test -p codex-utils-path-uri -p codex-config -p codex-mcp -p
codex-rmcp-client` (408 passed)
- `just test -p codex-cli -p codex-rmcp-client` (372 passed)
- `cargo check --workspace --tests`
- `just test` (11,311 passed; 43 unrelated environment/timing failures)
- `just fix -p codex-cli -p codex-config -p codex-core -p codex-mcp -p
codex-mcp-extension -p codex-rmcp-client -p codex-tui`
## Summary
- store MCP OAuth credentials in the configured auth credential backend
- support encrypted-local OAuth storage, including legacy keyring
migration
- propagate the credential backend through MCP refresh, session, CLI,
and app-server paths
## Stack
1. #27504 — config and feature flag
2. #27535 — auth-specific secret namespaces
3. #27539 — encrypted CLI auth storage
4. this PR — encrypted MCP OAuth storage
This is a parallel review stack; the original #17931 remains unchanged.
## Tests
- `just test -p codex-rmcp-client` (the transport round-trip test passed
after building the required `codex` binary and retrying)
- `just test -p codex-mcp`
- `just test -p codex-app-server
refresh_config_uses_latest_auth_keyring_backend`
- `just test -p codex-core
refresh_mcp_servers_is_deferred_until_next_turn`
- `just test -p codex-cli mcp`
- `just fix -p codex-rmcp-client -p codex-mcp -p codex-core -p codex-cli
-p codex-app-server -p codex-protocol`
- `just bazel-lock-check`
## Summary
- Retry transient streamable HTTP failures during RMCP startup when the
failure happens while sending the initialize request.
- Retry transient streamable HTTP failures for tools/list, which is
read-only and safe to replay.
- Cover both retryable HTTP statuses and request-layer failures where no
HTTP status is returned.
- Surface retryable HTTP statuses from the streamable HTTP adapter as
typed client errors.
- Add integration coverage for initialize retry, tools/list retry,
no-status request failure retry, and non-retryable initialize status.
## Root cause
The observed codex_apps failures can happen before normal tool
execution: RMCP startup fails while sending initialize, or the first
read-only tools/list fails after startup. Retrying hosted_apps_bridge
tools/call would not cover initialize and would risk replaying
side-effecting tool calls. This change retries the streamable HTTP
handshake itself, recreates the transport between initialize attempts,
and retries only tools/list among post-initialize service operations.
## Validation
- cargo fmt --package codex-rmcp-client
- cargo test -p codex-rmcp-client --test streamable_http_recovery
## Why
Persisted MCP OAuth credentials were reported as authenticated whenever
a credential record existed. An expired token without a usable refresh
token could therefore appear as `OAuth` even though startup could not
authenticate with it, leaving users with a misleading status instead of
a login prompt.
## What changed
- Classify stored OAuth credentials as missing, usable, or requiring
authorization.
- Reuse the existing refresh window so near-expiry credentials without a
refresh path are also treated as logged out.
- Validate required credential fields before reporting OAuth
authentication.
- Add unit coverage for credential usability and integration coverage
for expired, unexpired, and refreshable persisted credentials.
## Validation
- `just test -p codex-rmcp-client`
## Why
Codex persists OAuth expiry as an absolute `expires_at`, then
reconstructs RMCP’s relative `expires_in` when credentials are loaded.
For an already-expired token, Codex reconstructed `expires_in` as
missing.
[RMCP 0.15 treated a missing `expires_in` as zero when a refresh token
was
present](9cfc905a9e/crates/rmcp/src/transport/auth.rs (L704-L723)),
so this still triggered a refresh. [RMCP 1.7 treats missing expiry
information as unknown and uses the access token
as-is](3529c3675f/crates/rmcp/src/transport/auth.rs (L1233-L1265)),
causing the stale token to be sent during `initialize`.
## What changed
- Represent a known-expired persisted token as `expires_in = 0`,
preserving `None` for genuinely unknown expiry.
- Add Streamable HTTP coverage requiring the token to refresh before the
startup handshake.
## Validation
- The new regression test fails on RMCP 1.7 before the fix and passes
afterward.
- The same scenario passes on the commit immediately before the RMCP 1.7
update, using RMCP 0.15.
- `just test -p codex-rmcp-client` (63 passed).
WIll make it easier to uprev when the new draft spec is supported.
Also updates reqwest where needed for compatibility but doesn't update
it everywhere since this is already a large diff.
The new version of rmcp handles certain kinds of authentication failures
differently, this patch includes support for identifying the failing scope
in a WWW-Authenticate header.
## Why
Several bug reports describe thread shutdown (including subagent
threads) leaving stdio MCP server processes behind. These reports all
point at the same lifecycle gap: Codex launches stdio MCP servers, but
the session-level shutdown path does not explicitly close MCP clients or
terminate the server process tree.
Fixes#12491Fixes#12976Fixes#18881Fixes#19469
## History
This is best understood as a regression/coverage gap in MCP session
lifecycle management, not as stdio MCP cleanup being absent all along.
#10710 added process-group cleanup for stdio MCP servers, but that
cleanup only runs when the `RmcpClient`/transport is dropped. The older
reports (#12491 and #12976) came after that cleanup existed, which
suggests the remaining problem was that some higher-level shutdown paths
kept the MCP manager alive or replaced it without explicitly draining
clients. The newer reports (#18881 and #19469) exposed the same family
around manager replacement and shutdown.
## What changed
- Added an explicit stdio MCP process handle in `codex-rmcp-client` so
local MCP servers terminate their process group and executor-backed MCP
servers call the executor process terminator.
- Added `RmcpClient::shutdown()` and manager-level MCP shutdown draining
so session shutdown, channel-close fallback, MCP refresh, and connector
probing stop owned MCP clients.
- Added regression coverage that starts a stdio MCP server, begins an
in-flight blocking tool call, shuts down the client, and asserts the
server process exits.
## Verification
- `cargo test -p codex-rmcp-client`
- `cargo test -p codex-mcp`
- `just fix -p codex-rmcp-client`
- `just fix -p codex-mcp`
- `just fix -p codex-core`
- Manual before/after validation with a temporary repro script:
- Pre-fix binary from `HEAD^` (`fed0a8f4fa`): reproduced the leak with
surviving MCP server and child PIDs, `survivors=[77583, 77592]`,
`leaked=true`.
- Post-fix binary from this branch (`67e318148b`): verified both MCP
processes were gone after interrupting `codex exec`, `survivors=[]`,
`leaked=false`.
### Why
The RMCP layer needs a Streamable HTTP client that can talk either
directly over `reqwest` or through the executor HTTP runner without
duplicating MCP session logic higher in the stack. This PR adds that
client-side transport boundary so remote Streamable HTTP MCP can reuse
the same RMCP flow as the local path.
### What
- Add a shared `rmcp-client/src/streamable_http/` module with:
- `transport_client.rs` for the local-or-remote transport enum
- `local_client.rs` for the direct `reqwest` implementation
- `remote_client.rs` for the executor-backed implementation
- `common.rs` for the small shared Streamable HTTP helpers
- Teach `RmcpClient` to build Streamable HTTP transports in either local
or remote mode while keeping the existing OAuth ownership in RMCP.
- Translate remote POST, GET, and DELETE session operations into
executor `http/request` calls.
- Preserve RMCP session expiry handling and reconnect behavior for the
remote transport.
- Add remote transport coverage in
`rmcp-client/tests/streamable_http_remote.rs` and keep the shared test
support in `rmcp-client/tests/streamable_http_test_support.rs`.
### Verification
- `cargo check -p codex-rmcp-client`
- online CI
### Stack
1. #18581 protocol
2. #18582 runner
3. #18583 RMCP client
4. #18584 manager wiring and local/remote coverage
---------
Co-authored-by: Codex <noreply@openai.com>
## Summary
- Move local MCP stdio process startup behind a launcher trait.
- Preserve existing local stdio behavior while making transport creation
explicit.
## Stack
```text
o #18027 [6/6] Fail exec client operations after disconnect
│
o #18212 [5/6] Wire executor-backed MCP stdio
│
@ #18087 [4/6] Abstract MCP stdio server launching
│
o #18020 [3/6] Add pushed exec process events
│
o #18086 [2/6] Support piped stdin in exec process API
│
o #18085 [1/6] Add MCP server environment config
│
o main
```
---------
Co-authored-by: Codex <noreply@openai.com>
## Why
`argument-comment-lint` was green in CI even though the repo still had
many uncommented literal arguments. The main gap was target coverage:
the repo wrapper did not force Cargo to inspect test-only call sites, so
examples like the `latest_session_lookup_params(true, ...)` tests in
`codex-rs/tui_app_server/src/lib.rs` never entered the blocking CI path.
This change cleans up the existing backlog, makes the default repo lint
path cover all Cargo targets, and starts rolling that stricter CI
enforcement out on the platform where it is currently validated.
## What changed
- mechanically fixed existing `argument-comment-lint` violations across
the `codex-rs` workspace, including tests, examples, and benches
- updated `tools/argument-comment-lint/run-prebuilt-linter.sh` and
`tools/argument-comment-lint/run.sh` so non-`--fix` runs default to
`--all-targets` unless the caller explicitly narrows the target set
- fixed both wrappers so forwarded cargo arguments after `--` are
preserved with a single separator
- documented the new default behavior in
`tools/argument-comment-lint/README.md`
- updated `rust-ci` so the macOS lint lane keeps the plain wrapper
invocation and therefore enforces `--all-targets`, while Linux and
Windows temporarily pass `-- --lib --bins`
That temporary CI split keeps the stricter all-targets check where it is
already cleaned up, while leaving room to finish the remaining Linux-
and Windows-specific target-gated cleanup before enabling
`--all-targets` on those runners. The Linux and Windows failures on the
intermediate revision were caused by the wrapper forwarding bug, not by
additional lint findings in those lanes.
## Validation
- `bash -n tools/argument-comment-lint/run.sh`
- `bash -n tools/argument-comment-lint/run-prebuilt-linter.sh`
- shell-level wrapper forwarding check for `-- --lib --bins`
- shell-level wrapper forwarding check for `-- --tests`
- `just argument-comment-lint`
- `cargo test` in `tools/argument-comment-lint`
- `cargo test -p codex-terminal-detection`
## Follow-up
- Clean up remaining Linux-only target-gated callsites, then switch the
Linux lint lane back to the plain wrapper invocation.
- Clean up remaining Windows-only target-gated callsites, then switch
the Windows lint lane back to the plain wrapper invocation.
## Why
This is a follow-up to #15360. That change fixed the `arg0` helper
setup, but `rmcp-client` still coerced stdio transport environment
values into UTF-8 `String`s before program resolution and process spawn.
If `PATH` or another inherited environment value contains non-UTF-8
bytes, that loses fidelity before it reaches `which` and `Command`.
## What changed
- change `create_env_for_mcp_server()` to return `HashMap<OsString,
OsString>` and read inherited values with `std::env::var_os()`
- change `TransportRecipe::Stdio.env`, `RmcpClient::new_stdio_client()`,
and `program_resolver::resolve()` to keep stdio transport env values in
`OsString` form within `rmcp-client`
- keep the `codex-core` config boundary stringly, but convert configured
stdio env values to `OsString` once when constructing the transport
- update the rmcp-client stdio test fixtures and callers to use
`OsString` env maps
- add a Unix regression test that verifies `create_env_for_mcp_server()`
preserves a non-UTF-8 `PATH`
## How to verify
- `cargo test -p codex-rmcp-client`
- `cargo test -p codex-core mcp_connection_manager`
- `just argument-comment-lint`
Targeted coverage in this change includes
`utils::tests::create_env_preserves_path_when_it_is_not_utf8`, while the
updated stdio transport path is exercised by the existing rmcp-client
tests that construct `RmcpClient::new_stdio_client()`.
## Summary
- forward request-scoped task headers through MCP tool metadata lookups
and tool calls
- apply those headers to streamable HTTP initialize, tools/list, and
tools/call requests
- update affected rmcp/core tests for the new request_headers plumbing
## Testing
- cargo test -p codex-rmcp-client
- cargo test -p codex-core (fails on pre-existing unrelated error in
core/src/auth_env_telemetry.rs: missing websocket_connect_timeout_ms in
ModelProviderInfo initializer)
- just fix -p codex-rmcp-client
- just fix -p codex-core (hits the same unrelated auth_env_telemetry.rs
error)
- just fmt
---------
Co-authored-by: Codex <noreply@openai.com>
## What changed
- The pid-file cleanup test now keeps polling when the pid file exists
but is still empty.
- Assertions only proceed once the wrapper has actually written the
child pid.
## Why this fixes the flake
- File creation and pid writing are not atomic as one logical action
from the test’s point of view.
- The previous test sometimes won the race and read the file in the tiny
window after creation but before the pid bytes were flushed.
- Treating “empty file” as “not ready yet” synchronizes the test on the
real event we need: the wrapper has finished publishing the child pid.
## Scope
- Test-only change.
## Summary
- add one-time session recovery in `RmcpClient` for streamable HTTP MCP
`404` session expiry
- rebuild the transport and retry the failed operation once after
reinitializing the client state
- extend the test server and integration coverage for `404`, `401`,
single-retry, and non-session failure scenarios
## Testing
- just fmt
- cargo test -p codex-rmcp-client (the post-rebase run lost its final
summary in the terminal; the suite had passed earlier before the rebase)
- just fix -p codex-rmcp-client
This PR changes stdio MCP child processes to run in their own process
group
* Add guarded teardown in codex-rmcp-client: send SIGTERM to the group
first, then SIGKILL after a short grace period.
* Add terminate_process_group helper in process_group.rs.
* Add Unix regression test in process_group_cleanup.rs to verify wrapper
+ grandchild are reaped on client drop.
Addresses reported MCP process/thread storm: #10581
We started working with MCP in Codex before
https://crates.io/crates/rmcp was mature, so we had our own crate for
MCP types that was generated from the MCP schema:
8b95d3e082/codex-rs/mcp-types/README.md
Now that `rmcp` is more mature, it makes more sense to use their MCP
types in Rust, as they handle details (like the `_meta` field) that our
custom version ignored. Though one advantage that our custom types had
is that our generated types implemented `JsonSchema` and `ts_rs::TS`,
whereas the types in `rmcp` do not. As such, part of the work of this PR
is leveraging the adapters between `rmcp` types and the serializable
types that are API for us (app server and MCP) introduced in #10356.
Note this PR results in a number of changes to
`codex-rs/app-server-protocol/schema`, which merit special attention
during review. We must ensure that these changes are still
backwards-compatible, which is possible because we have:
```diff
- export type CallToolResult = { content: Array<ContentBlock>, isError?: boolean, structuredContent?: JsonValue, };
+ export type CallToolResult = { content: Array<JsonValue>, structuredContent?: JsonValue, isError?: boolean, _meta?: JsonValue, };
```
so `ContentBlock` has been replaced with the more general `JsonValue`.
Note that `ContentBlock` was defined as:
```typescript
export type ContentBlock = TextContent | ImageContent | AudioContent | ResourceLink | EmbeddedResource;
```
so the deletion of those individual variants should not be a cause of
great concern.
Similarly, we have the following change in
`codex-rs/app-server-protocol/schema/typescript/Tool.ts`:
```
- export type Tool = { annotations?: ToolAnnotations, description?: string, inputSchema: ToolInputSchema, name: string, outputSchema?: ToolOutputSchema, title?: string, };
+ export type Tool = { name: string, title?: string, description?: string, inputSchema: JsonValue, outputSchema?: JsonValue, annotations?: JsonValue, icons?: Array<JsonValue>, _meta?: JsonValue, };
```
so:
- `annotations?: ToolAnnotations` ➡️ `JsonValue`
- `inputSchema: ToolInputSchema` ➡️ `JsonValue`
- `outputSchema?: ToolOutputSchema` ➡️ `JsonValue`
and two new fields: `icons?: Array<JsonValue>, _meta?: JsonValue`
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/10349).
* #10357
* __->__ #10349
* #10356
This PR introduces a `codex-utils-cargo-bin` utility crate that
wraps/replaces our use of `assert_cmd::Command` and
`escargot::CargoBuild`.
As you can infer from the introduction of `buck_project_root()` in this
PR, I am attempting to make it possible to build Codex under
[Buck2](https://buck2.build) as well as `cargo`. With Buck2, I hope to
achieve faster incremental local builds (largely due to Buck2's
[dice](https://buck2.build/docs/insights_and_knowledge/modern_dice/)
build strategy, as well as benefits from its local build daemon) as well
as faster CI builds if we invest in remote execution and caching.
See
https://buck2.build/docs/getting_started/what_is_buck2/#why-use-buck2-key-advantages
for more details about the performance advantages of Buck2.
Buck2 enforces stronger requirements in terms of build and test
isolation. It discourages assumptions about absolute paths (which is key
to enabling remote execution). Because the `CARGO_BIN_EXE_*` environment
variables that Cargo provides are absolute paths (which
`assert_cmd::Command` reads), this is a problem for Buck2, which is why
we need this `codex-utils-cargo-bin` utility.
My WIP-Buck2 setup sets the `CARGO_BIN_EXE_*` environment variables
passed to a `rust_test()` build rule as relative paths.
`codex-utils-cargo-bin` will resolve these values to absolute paths,
when necessary.
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/8496).
* #8498
* __->__ #8496
